Digital-to-analog (D/A) converters are key elements in both electronic and photonic signal processing and data transmission. In many optical transmission systems, digital data has to be converted to analog form for processing and/or transmission. Indeed, there are many advantages for using optical technology to implementing D/A converters, for example, high-speed clocking and signal sampling, wide-bandwidth, light-weight components and the like. Additionally, a high-speed arbitrary analog waveform generator can be implemented using a very high-speed D/A converter.
One such optical D/A converter is described in an article entitle “Digital-to-Analog Conversion Using Electrooptic Modulators,” authored by Yacoubian, et al., IEEE Photonics Technology Letters, vol. 15, no. 1, January 2003, pages 117-119. However, the disclosed implementation is limited to a so-called 2-bit photonic D/A converter.
Noise also affects the operation of optical D/A converters. One source of noise arises from voltage excursions in the control signals that are provided to electro-optical elements D/A converter. Noise due to the voltage excursions tends to increase, sometimes dramatically, as D/A operating speed increases. Excessive noise can render an optical D/A inadequate for important, high-speed applications, including those noted above.
Accordingly, what is needed in the art is an optical D/A converter that converts digital input data to analog form with less noise. What is needed in the art is an optical D/A converter that is less susceptible to control signal voltage excursions.